There are several hand and upper extremity injury syndromes associated with cycling.

ULNAR NERVE NEUROPATHY (little finger and ring finger)

Numbness of the small and ring finger is the result of irritation of the Ulnar nerve.
After leaving the side of the neck, the ulnar nerve then travels through the arm pit,
down the arm to the hand and fingers. As it crosses the wrist, the ulnar nerve and artery
run through the tunnel known as Guyon's canal. The cause of Gunyon's Canal Syndrome
includes trauma to the area, fractures of the bones that form the floor of the tunnel,
and small, benign tumors of the nerve or surrounding tissues of the tunnel. Another
common cause of this syndrome is from pressure of bicycle handlebars seen with avid
cyclists. In that case it is overuse of the wrist, especially bending the wrist down
(flexing) and out, or putting constant pressure on the palm. Road vibration transmitted
through the handlebars may be the cause in some cases as well.

The symptoms begin with a feeling of pins and needles in the ring and little finger,
starting in the early morning before waking. This can progresses to a burning pain of
the wrist and hand, followed by decreased sensation and eventually clumsiness in the hand
as the ulnar nerve also supplies many of the small muscles of the hand.

The diagnosis of Guyons canal syndrome begins with a careful history and physical
examination by your doctor. Compression can occur at several areas along the ulnar
nerve, and your doctor will want to find exactly where the nerve is being affected.
Electrical studies such as Nerve Conduction (which measures how fast nerve impulses
travel along the nerve) may help to pin point your problem.

Treatment involves taking frequent breaks or limiting the amount of time you are
performing tasks that require flexing and turning out the wrist, or place constant
pressure on the palm. You will need to evaluate how you are gripping the handlebars,
particularly how you are holding your hand in relation to your forearm, and consider a
change in your riding/gripping style on the handlebars or hoods. Lowering your seat to
take pressure off your palm or wrist may be of help. Also consider increasing the
padding in your gloves or other measures to decrease the transmission of road vibration.
A wrist splint may be worn at night to decrease aggravating the condition.
Anti-inflammatory medications(such as ibuprofen or aspirin) may be helpful.
And in extreme cases surgery may be necessary to cut the ligament that forms the roof
of Guyons canal to relieve the pressure on the nerve. The ligament will eventually
heal back, but the canal will be larger than before thus providing more leeway in how
you position your wrist.

The most common surgical neuropathy is the compressive neuropathy of the Median Nerve
as it passes through the Carpal Tunnel in the wrist Irritation at this level in the
course of the median nerve causes numbness of the thumb and index fingers. As with Ulnar
neuropathy, it can be aggravated by wrist position and road vibration, and the approaches
to treatment are similar including changing the aggravating motion/position,
anti-inflammatories, and ultimately surgery if all else fails.

Common fixes for both

Ice and NSAIDs (motrin, ibuprofen) acutely

Use a firm but relaxed grip on the bar

Change hand positions frequently

Try padded gloves or cushy handlebar tape

Concentrate on keeping your wrists straight (bar ends on mountain bikes and aero
bars on a road bike keep the wrists in a more neutral position)

Alter your position on the bike to stay more upright (a higher stem or more spacers
in the headset)

SHOULDER PAIN

Developing shoulder pain is a common complaint, especially on long rides. A common
question I receive is similar to the following:

Q. We take a group of teens on a 400 mile bicycle trip every summer through
our church. One of the teens has complained extensively about shoulder
discomfort. What do you advise?

In this situation, shoulder pain on longer (than training) rides, the problem is generally
due to placing too much weight on the hands and riding with straight elbows (rather than
keeping them slightly flexed) which transmits more road shock to the arms and upper
body. Solutions include:

a more upright posture on the bike with less weight on outstretched arms

a higher stem

perhaps tilt the seat back a little (just a single click or it may put excessive
pressure on the perineum)

concentrating on keeping the elbows bent while riding

longer training rides - closer to the length of your long day on your next adventure